*/
#include <stdio.h>
+#include <openssl/bn.h>
#include "cryptlib.h"
#include "bn_lcl.h"
/* The old slow way */
#if 0
-int BN_div(dv, rem, m, d,ctx)
-BIGNUM *dv;
-BIGNUM *rem;
-BIGNUM *m;
-BIGNUM *d;
-BN_CTX *ctx;
+int BN_div(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m, const BIGNUM *d,
+ BN_CTX *ctx)
{
int i,nm,nd;
BIGNUM *D;
+ bn_check_top(m);
+ bn_check_top(d);
if (BN_is_zero(d))
{
BNerr(BN_F_BN_DIV,BN_R_DIV_BY_ZERO);
return(1);
}
- D=ctx->bn[ctx->tos];
- if (dv == NULL) dv=ctx->bn[ctx->tos+1];
- if (rem == NULL) rem=ctx->bn[ctx->tos+2];
+ D= &(ctx->bn[ctx->tos]);
+ if (dv == NULL) dv= &(ctx->bn[ctx->tos+1]);
+ if (rem == NULL) rem= &(ctx->bn[ctx->tos+2]);
nd=BN_num_bits(d);
nm=BN_num_bits(m);
/* The next 2 are needed so we can do a dv->d[0]|=1 later
* since BN_lshift1 will only work once there is a value :-) */
BN_zero(dv);
+ bn_wexpand(dv,1);
dv->top=1;
if (!BN_lshift(D,D,nm-nd)) return(0);
if (BN_ucmp(rem,D) >= 0)
{
dv->d[0]|=1;
- bn_qsub(rem,rem,D);
+ if (!BN_usub(rem,rem,D)) return(0);
}
/* CAN IMPROVE (and have now :=) */
if (!BN_rshift1(D,D)) return(0);
#else
-int BN_div(dv, rm, num, divisor,ctx)
-BIGNUM *dv;
-BIGNUM *rm;
-BIGNUM *num;
-BIGNUM *divisor;
-BN_CTX *ctx;
+int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor,
+ BN_CTX *ctx)
{
int norm_shift,i,j,loop;
BIGNUM *tmp,wnum,*snum,*sdiv,*res;
BN_ULONG d0,d1;
int num_n,div_n;
+ bn_check_top(num);
+ bn_check_top(divisor);
+
if (BN_is_zero(divisor))
{
BNerr(BN_F_BN_DIV,BN_R_DIV_BY_ZERO);
return(1);
}
- tmp=ctx->bn[ctx->tos];
+ tmp= &(ctx->bn[ctx->tos]);
tmp->neg=0;
- snum=ctx->bn[ctx->tos+1];
- sdiv=ctx->bn[ctx->tos+2];
+ snum= &(ctx->bn[ctx->tos+1]);
+ sdiv= &(ctx->bn[ctx->tos+2]);
if (dv == NULL)
- res=ctx->bn[ctx->tos+3];
+ res= &(ctx->bn[ctx->tos+3]);
else res=dv;
/* First we normalise the numbers */
/* Lets setup a 'window' into snum
* This is the part that corresponds to the current
* 'area' being divided */
+ BN_init(&wnum);
wnum.d= &(snum->d[loop]);
wnum.top= div_n;
- wnum.max= snum->max; /* a bit of a lie */
- wnum.neg= 0;
+ wnum.max= snum->max+1; /* a bit of a lie */
/* Get the top 2 words of sdiv */
/* i=sdiv->top; */
/* Setup to 'res' */
res->neg= (num->neg^divisor->neg);
- res->top=loop;
if (!bn_wexpand(res,(loop+1))) goto err;
+ res->top=loop;
resp= &(res->d[loop-1]);
/* space for temp */
if (BN_ucmp(&wnum,sdiv) >= 0)
{
- bn_qsub(&wnum,&wnum,sdiv);
+ if (!BN_usub(&wnum,&wnum,sdiv)) goto err;
*resp=1;
res->d[res->top-1]=1;
}
for (i=0; i<loop-1; i++)
{
- BN_ULONG q,n0,n1;
- BN_ULONG l0;
+ BN_ULONG q,l0;
+#ifdef BN_DIV3W
+ q=bn_div_3_words(wnump,d1,d0);
+#else
+
+#if !defined(NO_ASM) && !defined(PEDANTIC)
+# if defined(__GNUC__) && __GNUC__>=2
+# if defined(__i386)
+ /*
+ * There were two reasons for implementing this template:
+ * - GNU C generates a call to a function (__udivdi3 to be exact)
+ * in reply to ((((BN_ULLONG)n0)<<BN_BITS2)|n1)/d0 (I fail to
+ * understand why...);
+ * - divl doesn't only calculate quotient, but also leaves
+ * remainder in %edx which we can definitely use here:-)
+ *
+ * <appro@fy.chalmers.se>
+ */
+# define bn_div_words(n0,n1,d0) \
+ ({ asm volatile ( \
+ "divl %4" \
+ : "=a"(q), "=d"(rem) \
+ : "a"(n1), "d"(n0), "g"(d0) \
+ : "cc"); \
+ q; \
+ })
+# define REMAINDER_IS_ALREADY_CALCULATED
+# endif /* __<cpu> */
+# endif /* __GNUC__ */
+#endif /* NO_ASM */
+ BN_ULONG n0,n1,rem=0;
- wnum.d--; wnum.top++;
n0=wnump[0];
n1=wnump[-1];
if (n0 == d0)
+ {
q=BN_MASK2;
- else
- q=bn_div64(n0,n1,d0);
+#ifdef REMAINDER_IS_ALREADY_CALCULATED /* in this case it isn't */
+ rem=(n1-q*d0)&BN_MASK2;
+#endif
+ }
+ else /* n0 < d0 */
+#if defined(BN_LLONG) && defined(BN_DIV2W) && !defined(bn_div_words)
+ q=(BN_ULONG)(((((BN_ULLONG)n0)<<BN_BITS2)|n1)/d0);
+#else
+ q=bn_div_words(n0,n1,d0);
+#endif
{
#ifdef BN_LLONG
- BN_ULLONG t1,t2,rem;
- t1=((BN_ULLONG)n0<<BN_BITS2)|n1;
+ BN_ULLONG t2;
+
+#ifndef REMAINDER_IS_ALREADY_CALCULATED
+ /*
+ * rem doesn't have to be BN_ULLONG. The least we
+ * know it's less that d0, isn't it?
+ */
+ rem=(n1-q*d0)&BN_MASK2;
+#endif
+ t2=(BN_ULLONG)d1*q;
+
for (;;)
{
- t2=(BN_ULLONG)d1*q;
- rem=t1-(BN_ULLONG)q*d0;
- if ((rem>>BN_BITS2) ||
- (t2 <= ((BN_ULLONG)(rem<<BN_BITS2)+wnump[-2])))
+ if (t2 <= ((((BN_ULLONG)rem)<<BN_BITS2)|wnump[-2]))
break;
q--;
+ rem += d0;
+ if (rem < d0) break; /* don't let rem overflow */
+ t2 -= d1;
}
#else
- BN_ULONG t1l,t1h,t2l,t2h,t3l,t3h,ql,qh,t3t;
- t1h=n0;
- t1l=n1;
+ BN_ULONG t2l,t2h,ql,qh;
+
+#ifndef REMAINDER_IS_ALREADY_CALCULATED
+ /*
+ * It's more than enough with the only multiplication.
+ * See the comment above in BN_LLONG section...
+ */
+ rem=(n1-q*d0)&BN_MASK2;
+#endif
+#ifdef BN_UMULT_HIGH
+ t2l = d1 * q;
+ t2h = BN_UMULT_HIGH(d1,q);
+#else
+ t2l=LBITS(d1); t2h=HBITS(d1);
+ ql =LBITS(q); qh =HBITS(q);
+ mul64(t2l,t2h,ql,qh); /* t2=(BN_ULLONG)d1*q; */
+#endif
+
for (;;)
{
- t2l=LBITS(d1); t2h=HBITS(d1);
- ql =LBITS(q); qh =HBITS(q);
- mul64(t2l,t2h,ql,qh); /* t2=(BN_ULLONG)d1*q; */
-
- t3t=LBITS(d0); t3h=HBITS(d0);
- mul64(t3t,t3h,ql,qh); /* t3=t1-(BN_ULLONG)q*d0; */
- t3l=(t1l-t3t)&BN_MASK2;
- if (t3l > t1l) t3h++;
- t3h=(t1h-t3h)&BN_MASK2;
-
- /*if ((t3>>BN_BITS2) ||
- (t2 <= ((t3<<BN_BITS2)+wnump[-2])))
- break; */
- if (t3h) break;
- if (t2h < t3l) break;
- if ((t2h == t3l) && (t2l <= wnump[-2])) break;
-
+ if ((t2h < rem) ||
+ ((t2h == rem) && (t2l <= wnump[-2])))
+ break;
q--;
+ rem += d0;
+ if (rem < d0) break; /* don't let rem overflow */
+ if (t2l < d1) t2h--; t2l -= d1;
}
#endif
}
+#endif /* !BN_DIV3W */
l0=bn_mul_words(tmp->d,sdiv->d,div_n,q);
+ wnum.d--; wnum.top++;
tmp->d[div_n]=l0;
for (j=div_n+1; j>0; j--)
if (tmp->d[j-1]) break;
}
#endif
+
+/* rem != m */
+int BN_mod(BIGNUM *rem, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx)
+ {
+#if 0 /* The old slow way */
+ int i,nm,nd;
+ BIGNUM *dv;
+
+ if (BN_ucmp(m,d) < 0)
+ return((BN_copy(rem,m) == NULL)?0:1);
+
+ dv= &(ctx->bn[ctx->tos]);
+
+ if (!BN_copy(rem,m)) return(0);
+
+ nm=BN_num_bits(rem);
+ nd=BN_num_bits(d);
+ if (!BN_lshift(dv,d,nm-nd)) return(0);
+ for (i=nm-nd; i>=0; i--)
+ {
+ if (BN_cmp(rem,dv) >= 0)
+ {
+ if (!BN_sub(rem,rem,dv)) return(0);
+ }
+ if (!BN_rshift1(dv,dv)) return(0);
+ }
+ return(1);
+#else
+ return(BN_div(NULL,rem,m,d,ctx));
+#endif
+ }
+
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